The story of how this mish-mosh of languages saved the Jews is told In the best story-telling tradition and soild, scholarly research of Robin McNeil and Robert McCrumm's The Story of English, and Simon Winchester's The Meaning of Everything,
Yiddish--an oft-considred "gutter language--is an unlikely survivor the ages, much like the Jews themselves. Its survival has been an incredible journey, especially considering how often Jews have tried to kill it themselves.